Polyurethanes are suitable for a large number of applications. To modify the polyurethanes behavior when exposed to fire, flame-retarding agents are usually added to these polyurethane materials. Phosphorous compounds, such as phosphates, phosphonates, and phosphites, are effective flame-retarding agents for polyurethane foam. In general phosphorus compounds may provide fire retardant activity through a combination of condensed phase reactions, gas phase radical quenching, polymer carbonization promotion, and/or char formation.
However, many phosphorus compounds are not soluble in the polyol formulations used to produce the polyurethanes. Therefore, there is a need for phosphorus compounds which are more compatible with the polyurethane formulations.